/Engine/Plugins/Online/OnlineServices/Source/OnlineServicesCommon/Public/Online/SessionsCommon.h
This event will trigger as a result of leaving or destroying a session.
virtual [TOnlineEvent](API\Plugins\OnlineServicesInterface\Online\TOnlineEvent)< void(const [FSessionLeft](API\Plugins\OnlineServicesInterface\Online\FSessionLeft) &)> OnSessionLeft()